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FAA Fumbled Its Response to a Surge in GPS Jamming

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Re: FAA Fumbled Its Response to a Surge in GPS Jamming

#81

Post by throw0101a »

aaronfitz wrote: post #63
omegant wrote: post #56

Earlier quoted context omitted.

We still have inertial and radio beacon navigation(VOR, ADF, ILS) , you are always able to disconnect the gps data from the computer. Obviously GPS is allowing much more precise route and approach navigation, all without ground equipment. New rules and rutes have been developed the last 15 years to take advantage of GPS precision and global availability. But current airplanes still keep all the old systems in place a…

The waves of deactivations on the ground stations have already started. We're on a trajectory of GPS over-reliance. https://www.boldmethod.com/learn-to-fly/navigation/the-faa-i... https://www.aopa.org/news-and-media/all-news/2018/may/23/vor...

From the first (2016) article:

> 10 years from now, the network of VORs will be about 68% the size it currently is.

So they're cutting about one-third of the VORs by the end of the phase out.

Re: FAA Fumbled Its Response to a Surge in GPS Jamming

#82

Post by Rebelgecko »

linuxhansl wrote: post #33

As a lay person in this area... There are more navigation systems around: The EU Galileo, Russia's GLONASS, etc. Assuming it's unlikely that all system are down/jammed/compromised in the same area at the same time, receivers for multiple systems should be OK...? (Again lay person here)

GPS and Galileo have overlapping frequencies (this is by design) so if GPS is jammed then Galileo probably won't be available either.

GLONASS is historically less accurate and available than GPS (at least at lower latitudes) so I wouldn't be surprised if fewer (or no) aircraft have hardware for it

Re: FAA Fumbled Its Response to a Surge in GPS Jamming

#83

Post by mike_d »

jdavis703 wrote: post #50
ryandrake wrote: post #36

> "Aircraft are greatly affected by the GPS jamming and it's not taken seriously by management," reads one report. "We've been told we can't ask to stop jamming, and to just put everyone on headings." This is the military practicing, but I would hope that civilian airline transport operations are also robust to GNSS unavailability or denial. Even private pilots in little Cessnas are taught to navigate using radio-nav…

In the examples given it sounds like ATC was doing things like directing aircraft in to restricted air space. Obviously the captain has final say and ATC’s role is officially just advisory. But this sounds like a bit more than a pilot who forgot how to navigate.

> ATC was doing things like directing aircraft in to restricted air space

The last US government GPS denial test was large enough that it impacted ATC from Seattle to Los Angeles to Denver to Albuquerque.

They didn't really have a way to route around it.

Re: FAA Fumbled Its Response to a Surge in GPS Jamming

#84

Post by oceanplexian »

topspin wrote: post #52
gh02t wrote: post #24

Earlier quoted context omitted.

The signal GPS uses is actually very very weak and can be jammed pretty easily just by spewing a bunch of noise in the general area of the spectrum where it lies. Military grade receivers have some countermeasures that civilian equipment doesn't (e.g. the military signals have much wider bandwidth to work with, and you can also do some antenna magic), but jamming is still a problem for them too and it's a pretty acti…

"and you can also do some antenna magic" Just thinking about what that would involve. Very high gain antennas could track individual GPS satellites and probably defeat jammers. A phased array system (similar to Starlink's 'dishy', but probably larger due to the much lower frequency) might also work. Either solution would make many if not most uses of GPS either physically impractical and/or too costly.

You can defeat jamming in a fairly unsophisticated way by using an antenna that can only receive signals from a specific direction (i.e straight up), while everything else is filtered out. If the jammer is to the side or below you it wouldn’t do much good. The problem is for GPS to work you need to be able to see a few of the sats and some will be closer to the horizon.

Re: FAA Fumbled Its Response to a Surge in GPS Jamming

#85

Post by topspin »

oceanplexian wrote: post #84
topspin wrote: post #52

Earlier quoted context omitted.

"and you can also do some antenna magic" Just thinking about what that would involve. Very high gain antennas could track individual GPS satellites and probably defeat jammers. A phased array system (similar to Starlink's 'dishy', but probably larger due to the much lower frequency) might also work. Either solution would make many if not most uses of GPS either physically impractical and/or too costly.

You can defeat jamming in a fairly unsophisticated way by using an antenna that can only receive signals from a specific direction (i.e straight up), while everything else is filtered out. If the jammer is to the side or below you it wouldn’t do much good. The problem is for GPS to work you need to be able to see a few of the sats and some will be closer to the horizon.

"antenna that can only receive signals from a specific direction"

That's what "high gain" means; the main lobe is strongly focused in some direction. Actively tracking multiple moving satellites makes this approach mostly unworkable.

Re: FAA Fumbled Its Response to a Surge in GPS Jamming

#86

Post by SAI_Peregrinus »

mywittyname wrote: post #44
xxpor wrote: post #16

Earlier quoted context omitted.

That's like saying just pretend the internet is down. The goal is to find unanticipated uses.

Also, "jamming" can include sending distorted signals. These distortions can be a spoofed or malformed packet of data. Knowing what happens when a navigation tool suddenly thinks the vehicle is on the other side of the world is important. As is, ensuring that a garbage signal won't crash it.

Or less extreme things. Do the soldiers notice when their GPS shows them as half a mile away from where they need to be. In a slowly changing offset.

Re: FAA Fumbled Its Response to a Surge in GPS Jamming

#87

Post by dwheeler »

aaronfitz wrote: post #63
omegant wrote: post #56

Earlier quoted context omitted.

We still have inertial and radio beacon navigation(VOR, ADF, ILS) , you are always able to disconnect the gps data from the computer. Obviously GPS is allowing much more precise route and approach navigation, all without ground equipment. New rules and rutes have been developed the last 15 years to take advantage of GPS precision and global availability. But current airplanes still keep all the old systems in place a…

The waves of deactivations on the ground stations have already started. We're on a trajectory of GPS over-reliance. https://www.boldmethod.com/learn-to-fly/navigation/the-faa-i... https://www.aopa.org/news-and-media/all-news/2018/may/23/vor...

Bad idea. Relying on any single technology creates a nasty single point of failure. GPS signals are weak signals from satellites & obviously can be jammed.

Re: FAA Fumbled Its Response to a Surge in GPS Jamming

#88

Post by mike_d »

topspin wrote: post #52
gh02t wrote: post #24

Earlier quoted context omitted.

The signal GPS uses is actually very very weak and can be jammed pretty easily just by spewing a bunch of noise in the general area of the spectrum where it lies. Military grade receivers have some countermeasures that civilian equipment doesn't (e.g. the military signals have much wider bandwidth to work with, and you can also do some antenna magic), but jamming is still a problem for them too and it's a pretty acti…

"and you can also do some antenna magic" Just thinking about what that would involve. Very high gain antennas could track individual GPS satellites and probably defeat jammers. A phased array system (similar to Starlink's 'dishy', but probably larger due to the much lower frequency) might also work. Either solution would make many if not most uses of GPS either physically impractical and/or too costly.

GPS has a type of frequency hopping. Rather than jumping around from frequency to frequency, it slides up and down the spectrum like if you were turning an analog knob. The movements are determined by a pseudo random number generator unique to each satellite. Civilian GPS receivers have these PRNG keys so they can follow the movements up and down and stay locked on to the carrier while filtering any potential interference or jamming.

For military use they have a second PRNG that lines up with the civilian PRNG once every 10 cycles. So between every ping your phone or car GPS gets, there are 9 more military only ones that move around the spectrum randomly and have some other security features.

To jam GPS you either need the PRNG keys to know when to move your jamming, or just blanket the entire spectrum with random noise. If you take the blanket everything approach receivers may still be able to pick out the carrier (because it is moving and a detectable change).

(This isn't actually how it works, but is a simplified example of the concept. GPS is an amazing protocol that I don't even understand most of. There is some really cool stuff like using two different frequencies to measure the delay introduced by the ionosphere. The Coast Guard manages a lot of the civilian side of things and has plenty of rabbit holes you can go down: https://www.navcen.uscg.gov/?pageName=GPSmain)

Re: FAA Fumbled Its Response to a Surge in GPS Jamming

#89

Post by nradov »

agent327 wrote: post #57

Does this kind of jamming also affect road traffic in the area, or only air traffic? Just curious...

Yes GNSS jamming and spoofing can interfere with road navigation. Due to signal propagation limits imposed by the ground and other obstacles the effective range will typically be shorter than with aircraft.

https://money.cnn.com/2016/12/02/technology/kremlin-gps-sign...

Re: FAA Fumbled Its Response to a Surge in GPS Jamming

#90

Post by throw0101a »

bdash wrote: post #76
anyfoo wrote: post #54

Earlier quoted context omitted.

Are they still taught to do NDB approaches? I thought that's been phased out, too. In fact I was told the other day that the US officially tuned off the NDBs? Does not apply to VORs then, but as you say, the fact that they get phased out more and more is concerning.

Most VORs are being phased out as well, with only a minimum network left in place to support routing flights on instrument flight plans to airports with non-GPS approaches (i.e., ILS) in the event of a GPS outage. [1]: https://www.aopa.org/advocacy/airports-and-airspace/navigati...

> Most VORs are being phased out as well […]

"Most" VORs are not being phased out. The FAA is going from around 950 to about 590: about one-third are being retired.

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